Atlantic Basin Tropical Cyclones

Hurricane Ian Forecast Discussion


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WTNT44 KNHC 292059
TCDAT4

Hurricane Ian Discussion Number  29
NWS National Hurricane Center Miami FL       AL092022
500 PM EDT Thu Sep 29 2022

Ian remains a hybrid tropical cyclone with characteristics of an
extratropical low, including a comma-pattern on satellite images
and some frontal features in the outer circulation.  The cyclone
continues to have a warm core, however, and all indications are that
it will re-develop strong convection over the center overnight.
Based on Melbourne Doppler radar velocity data of persistent 70-80-
kt winds from 5-10 thousand feet, and earlier sustained winds of
about 60 kt near that band from an observation in New Smyrna Beach,
the initial wind speed is raised to 65 kt.  This makes Ian a
hurricane again.   An Air Force Reserve Hurricane Hunter aircraft
is scheduled to fly through Ian this evening and will provide a
better intensity estimate.

Ian finally appears to be making more of a turn to the north-
northeast this afternoon.  The hurricane should turn to the north
overnight due to the incoming trough diving southward over the
southern United States and then north-northwestward on Saturday
with an increase in forward speed.  While the overall synoptic
pattern is similar in all of the models, Ian has been uncooperative
and remains right of the previous track.  Thus, the new forecast is
adjusted to the east, and lies east of the model consensus.
Assuming Ian re-develops thunderstorms near the core overnight, it
should take the expected north-northwest turn, but this shouldn't 
be considered a confident forecast yet.  Because of the 
uncertainty, the Hurricane Warning has been extended eastward into 
North Carolina to Cape Fear.

The hurricane is moving over the Gulf Stream for the next day or
so, where it has some time for further re-intensification.
Additionally, the trough interaction should provide a baroclinic
energy kick.  These factors point to some strengthening before
landfall tomorrow.  The new forecast is close to the GFS and
regional hurricane models and is a bit stronger than before.  It
should be emphasized that while we don't expect Ian to be a classic
hurricane at landfall, this does not diminish the danger it poses.
Strong winds and storm surge will also extend far from the center
and will begin well before the center arrives.


Key Messages:

1. There is a danger of life-threatening storm surge through Friday
along the coasts of northeast Florida, Georgia, and South Carolina.
Residents in these areas should follow any advice given by local
officials.

2. Hurricane-force winds are expected across coasts of South
Carolina and southeastern North Carolina beginning early Friday,
where a Hurricane Warning is in effect. Hurricane conditions are
possible by tonight along the coasts of northeastern Florida,
Georgia, and North Carolina where a Hurricane Watch is in 
effect.   Preparations should be rushed to completion since 
tropical-storm-force winds will begin well before the center 
approaches the coast.

3. Ongoing major-to-record river flooding will continue across
portions of central Florida, with considerable flooding in northern
Florida.  Considerable flash and urban flooding is expected across
coastal portions of northeast Florida through Friday. Local
significant flooding in southeastern Georgia and eastern South
Carolina is expected through the end of the week.


FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 29.3N  79.9W   65 KT  75 MPH
 12H  30/0600Z 30.5N  79.4W   70 KT  80 MPH
 24H  30/1800Z 32.8N  79.6W   70 KT  80 MPH
 36H  01/0600Z 35.0N  80.4W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  01/1800Z 36.5N  81.0W   15 KT  15 MPH...POST-TROP/EXTRATROP
 60H  02/0600Z...DISSIPATED

$$
Forecaster Blake



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